Presently, a directly assistance call is initiated when a telephone subscriber dials a predetermined telephone number such as 411 or 555-1212. The directory assistance call is routed by the public telephone network to a special switch known as an automatic call distributor or ACD. One commonly used type of ACD is known as the No.5 crossbar ACD.
On an incoming side, the ACD is connected to a plurality of directory assistance trunks. On an outgoing side, the ACD is connected to a plurality of operator positions. The ACD serves to connect a directory assistance call arriving on one of the directory assistance trunks to the first available operator position. If no operator position is available for an incoming directory assistance call when it arrives, the ACD queues the call and transmits appropriate signals back through the telephone network so that the subscriber who made the directory assistance call hears ringing. When an operator position becomes available, the ACD connects the directory assistance call which has been queued the longest to the available operator position.
When a directory assistance call is connected by an ACD to an operator position, the operator at that position hears a beep tone indicating a directory assistance call has been connected to that position. Then, either the operator says a greeting or a recording device, with a greeting prerecorded by the operator, automatically plays a greeting to the subscriber while the operator is listening. The subscriber then provides information about a requested telephone listing. Based on this information the operator uses a keyboard to query a directory assistance data base to obtain the requested telephone number. If necessary, during this process, the operator asks the subscriber for more information. Once the requested telephone number is identified by the operator, it is presented verbally to the subscriber. Currently, in most locations, this spoken information is usually generated by an automated voice system without the operator being on line.
Between the time a directory assistance call arrives at an ACD and the time when the customer finishes speaking the initial directory assistance request, there are several distinct intervals. These intervals are:
(1) a queuing interval, during which the call waits at the ACD for an available operator position. It is during this queuing delay that ringing is heard by the customer. This interval ranges from less than 0.5 second to over 10.0 seconds. During periods of high traffic volumes when team sizes are large, the average queuing interval is typically about 2.0 seconds. During periods of low traffic volumes when team sizes are small, such as early morning, late evening and nights, the average queuing delay is typically about 6.0 seconds.
(2) a greeting interval, during which the operator says a greeting or a greeting is played by a recording device at the operator's position. This interval typically lasts about 1.0 seconds, and
(2) a request interval, wherein the subscriber speaks the initial directory assistance request and the operator hears the initial request, i.e., "Ahhh, yes. In Morristown, the number for the City Hall." This interval typically ranges between 2.0 and 8.0 seconds, and averages around 4.0 seconds.
Based on the averages described above, the average time consumed by the sum of the queuing interval, the greeting interval and the request interval averages about 7.0 seconds during busy periods of the day when large teams of operators are used, and 11.0 seconds during periods of lighter traffic volumes when small teams of operators are used. The difference is due to the longer queuing delays encountered during periods of smaller team size. The customer is involved in the call during this entire period.
On the other hand, the operator only participates during the greeting interval and the request interval, not during the period of queuing delay. Thus, the average working time of the operator for the above-described portion of a directory assistance call typically ranges from 3.0 to 9.0 seconds, and typically averages about 5.0 seconds (1.0 second for the greeting interval and 4.0 seconds for the initial directory assistance request).
Speech compression is a method for processing speech so that a listener can hear it in less time than the speaker took to say it. This compression can be accomplished without changing the pitch of the speaker's voice. Speech processing systems which can compress speech are available, for example, from the DSP Group, Inc., Emeryville, Calif.
Illustratively, to compress speech, a processing system analyzes the spectral content of a speech signal and detects the speed at which this spectral information changes. The speech processing system utilizes this information to determine the degree to which the speech signal can be compressed. Compression involves removing bits of redundant information. Alternatively, or in conjunction with speech compression, other speech processing techniques such as silence deletion, automatic speech recognition, etc. may be implemented to reduce the time required to hear subscriber's speech.
In a directory assistance call, for example, if a subscriber responds to the initial greeting "Ahhhh, yes. In Morristown, the number for the City Hall," the speech processing system recognizes that the "Ahhhh" is essentially a long constant vowel, where a substantial portion can be removed so that what remains sounds like "Ah." Using this approach, the speech signal of a slow talker is speeded up relatively more than that of a fast talker.
It is an object of the present invention to apply speech compression technology to the above-described directory assistance calls to significantly reduce the average working time of an operator for a directory assistance call.